Fet band amplifier
AssigneeNiigata Seimitsu Co., Ltd.
InventorHiroshi Miyagi
Life of this patent
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Abstract
An FET band amplifier for reducing a residual noise during gain control. An FET band amplifier 5 included in an AM receiver comprises amplifiers 11 to 15 e.g. at five stages, a BPF 16 inserted halfway in their connection, and an AGC circuit 8. The BPF 16 allows the passage of a component of a band wider than the amplification band of the whole of the FET band amplifier and reduces a 1/f noise by removing a low-band component of a signal output from the amplifier 13 at the third stage and thermal noise by removing the high-band component. This process enables a reduction in a residual noise during gain control included in a signal output from the amplifier 15 at the final stage.
Claims33
An FET band amplifier, comprising a multistage amplifier and a gain control circuit that controls a gain of the multistage amplifier,
- wherein said multistage amplifier comprises amplifiers of multiple stages cascaded in which FETS are used as amplification elements, and a band-pass filter inserted in mid-stage of the amplifiers of multiple stages and adjusted to have a passing band wider than an amplification band, and
- p-channel FETs are used as said FETs of at least first to nth-stage amplifiers of said amplifiers.
An FET band amplifier, comprising a multistage amplifier that comprises amplifiers of multiple stages cascaded in which FETs are used as amplification elements, and a gain control circuit that controls a gain of the multistage amplifier,
- wherein said amplifier of each stage has a high-band component elimination unit for eliminating components of bands higher than the upper limit of amplification band components from input/output signals and a low-band component elimination unit for eliminating components of bands lower than the lower limit of said amplification band components from said input/output signals, and
- p-channel FETs are used as said FETs of at least first to nth-stage amplifiers of said amplifiers.
An FET band amplifier, comprising a multistage amplifier that comprises amplifiers of multiple stages cascaded in which FETs are used as amplification elements, and a gain control circuit that controls a gain of the multistage amplifier,
- wherein said amplifier of each stage has a high-band component elimination unit for eliminating components of bands higher than the upper limit of amplification band components from input/output signals,
- p-channel FETs are used as said FETs of at least first to nth-stage amplifiers of said amplifiers, and
- the FET band amplifier comprises a feedback circuit returning back components of bands lower than the lower limit of said amplification band components included in an output signal of the final-stage amplifier of said amplifiers to the first-stage amplifier of said amplifiers in the state of an inverted phase.
An FET band amplifier, comprising a multistage amplifier that comprises amplifiers of multiple stages cascaded in which FETs are used as amplification elements, and a gain control circuit that controls a gain of the multistage amplifier,
- wherein p-channel FETs are used as the amplification elements included in first to mth-stage amplifiers of said amplifiers.
Dependencies are inferred from the claim text.